Real-time optical image subtraction and edge enhancement using ferroelectric liquid-crystal devices based on speckle modulation

Abstract

We carried out real-time optical image subtraction and edge enhancement based on a speckle modulation technique by using ferroelectric liquid-crystal polarization switches and a ferroelectric liquid-crystal spatial light modulator. A ferroelectric liquid-crystal spatial light modulator is employed as a real-time and multiple-exposure optical device, and successful results are obtained from three-exposure images modulated by speckles. Thus, image subtraction and edge enhancement are realized in real time. The whole operation is performed within several milliseconds with modest operating conditions. Because the spatial light modulator has a high resolution of greater than 100 line pairs/mm and can store fine speckle patterns, the image qualities we obtained are quite satisfactory.

Real-time edge detection by cyclic-path polarization interferometer

“…A scheme to implement this in near real time is demonstrated using an SLM, where the low-frequency image is generated by spatial filtering in one of the mirrors of a Twymann-Green interferometer setup employing a polarizing beam splitter (PBS), and subtraction between the orthogonally polarized images is achieved by transmission through a suitably oriented polarizer before the recording plane [12]. It has also been demonstrated that subtraction between speckle modulated and speckle shifted images, using ferroelectric polarization switches and an optically addressed SLM, leads to extraction of the difference image [13]. However, the two images to be subtracted are derived from two different object transparencies and as such, may not be adapted for edge detection.…”

Theoretical Analysis of Optically Addressed Spatial Light Modulator with Electromagnetic Driven Micromirror for Optical Information Processing

“…Lin et al. performed that real-time image subtraction and edge enhancement by using a ferroelectric liquid-crystal SLM based on the speckle modulation technique [3]. Takahashi and Ishii proposed the dual liquid-crystal SLMs for real-time matched filtering, which was used as both an amplitude-input and a multilevel phase-only filter [4].…”